Methods for removing acid gases from gas streams are known from practice. It has proven useful in a stripping column to extract the acid gases from a natural gas stream, for example by physically acting absorbing agents. In this manner most of the acid-gas components can be removed from the gas stream. However, it is a disadvantage in the methods known from practice that a required virtually complete removal of the acid gas components is possible only with a disproportionately high expenditure. This means in particular that a voluminous scrubbing liquid circulation and/or large packing heights are necessary in an absorber column or a stripper column. Furthermore, methods are known from practice in which scrubbing agents are used that contain a physically acting absorbing agent and a chemically acting scrubbing agent and water.
A method is known from DE 10 2005 050 385 [US 2008/0236390] for removing carbon dioxide from gas streams. A mixture of a primary or secondary amine in an aqueous solution, a physical solvent (for example, acetylmorpholine, N-formylmorpholine) and optionally further amines are used as an absorbing agent. The proportion of the morpholine in the absorbing agent is up to 25%.
It is a disadvantage of the known methods, in particular when high acid-gas partial pressures are present, that due to the proportion of the chemical scrubbing agent and water in the absorbent, the proportion of the physically acting absorbing agent has to be reduced, so that the capacity of the physically acting absorbing agent is reduced. It is furthermore disadvantageous that as a result of the water content in the absorbent, in particular with high acid gas partial pressures, increasing corrosion is to be expected in the devices in which the methods are carried out.